U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2015-1011

Prepared in cooperation with the Bureau of Reclamation

Simulated Runoff at Many Locations in the 

Methow River Basin, Washington
Cover: Sketch titled “Methow Valley,” by Sue Van Etten, Langley, Washington. Obtained with permission from the artist, October 2014.
Simulated Runoff at Many Stream Locations in the 

Methow River Basin, Washington

By Mark Mastin

Prepared in cooperation with the Bureau of Reclamation

Open-File Report 2015-1011

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015 

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Suggested citation:

Mastin, Mark, 2015, Simulated runoff at many stream locations in the Methow River Basin, Washington: U.S. 

Geological Survey Open-File Report 2015-1011, 22 p., http://dx.doi.org/10.3133/ofr20151011. 

ISSN 2331-1258 (online)
iii

Contents

Abstract ...................................................................................................................................................................... 1

Introduction................................................................................................................................................................. 1

Purpose and Scope................................................................................................................................................. 2

Basin Description........................................................................................................................................................ 2

Watershed Model........................................................................................................................................................ 5

Development of the Model for the Methow River Basin .......................................................................................... 5

Construction of the PRMS Model for the Methow River Basin ................................................................................ 6

Input Data File..................................................................................................................................................... 6

Diversions and Applications ................................................................................................................................ 9

Stream Segments.............................................................................................................................................. 11

Simulated Runoff at Stream Locations ..................................................................................................................... 13

Summary .................................................................................................................................................................. 19

References Cited...................................................................................................................................................... 19

Appendix A. Simulated and Observed Mean Monthly and Annual Runoff for Six Streamflow-Gaging Stations

for the Period of Record that the Station Was Active During Water Years 1988–2013............................................. 21

Figures

Figure 1. Map showing location of U.S. Geological Survey streamflow-gaging stations in the 

Methow River Basin, Washington.............................................................................................................................. 3

Figure 2. Graphs showing mean monthly discharge for water years 1988–2013 at two streamflow-gaging 

stations in the Methow River Basin, Washington....................................................................................................... 4

Figure 3. Map showing data-collection network used for the watershed model for the Methow River Basin, 

Washington................................................................................................................................................................ 7

Figure 4. Map showing U.S. Geological Survey (USGS) streamflow-gaging stations, flow-routing segments, and 

hydrologic response units for the watershed model for the Methow River Basin, Washington ................................ 12

Figure 5. Graph showing annual mean runoff for Methow River near Pateros, Washington (USGS Station No. 

12449950). .............................................................................................................................................................. 14

Figure 6. Graphs showing simulated and observed mean monthly runoff for indicated water years (WY) for six 

selected streamflow-gaging stations in the Methow River Basin, Washington......................................................... 15

Tables

Table 1. Streamflow-gaging and meteorological stations by agency collecting the data, period of record, and the 

position in the data input file, Methow River Basin, Washington................................................................................ 8

Table 2. Simulated irrigation diversions, Methow River Basin, Washington.).......................................................... 10

Table 3. Index value for the flow-routing variables segment_cfs and tosegment in the Methow watershed model 

and the associated streamflow-gaging station and period of record if co-located or the stream location................. 17
iv

Conversion Factors

Inch/Pound to International System of Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

inch per day (in/d) 2.54 centimeter per day (cm/d)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

International System of Units to Inch/Pound

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

Abbreviations

GIS geographic information system

GSFLOW groundwater and surface-water flow model

HRU hydrologic response unit

PRMS Precipitation Runoff Modeling System

USGS U.S. Geological Survey
1 

Simulated Runoff at Many Stream Locations in the 

Methow River Basin, Washington

By Mark Mastin

Abstract

A collaborative Bureau of Reclamation-U.S. Geological Survey (USGS) team has been brought 

together to incorporate a conceptual geomorphic-habitat model with a process-based trophic model to 

understand the processes important to stream habitat for anadromous fish populations. The Methow 

River Basin was selected as a test basin for this hybrid geomorphic-habitat/trophic model, and one of 

the required model inputs is long-term daily runoff at reaches with potential habitat. Leveraging the 

existence of a watershed model that was constructed for the Methow River Basin by the USGS, the team 

approached the USGS at the Washington Water Science Center to resurrect the original model and to 

simulate runoff at many locations in the basin to test the trophic model. Thirteen new flow-routing sites 

were added to the model, creating a total of 61 sites in the basin where daily runoff was simulated and 

provided as output. The input file that contains observed meteorological data that drives the watershed 

model and observed runoff data for comparisons with simulated runoff was extended from water year 

2001 to water year 2013 using data from 18 meteorological sites and 12 observed runoff sites. The 

watershed model included simulation of 16 irrigation diversions that simulated 50-percent water loss 

through canal seepage. Irrigation was simulated as a constant application of 0.2 inches per day to during 

the irrigation season, May 1–October 7. 

Comparisons of the simulated runoff with observed runoff at six selected long-term streamflowgaging stations showed that the simulated annual runoff was within +15.4 to -9.6 percent of the annual 

observed runoff. The simulated runoff generally matched the seasonal flow patterns, with bias at some 

stations indicated by over-simulation of the October–November late autumn season and undersimulation of the snowmelt runoff months of May and June. Sixty-one time series of daily runoff for a 

26-year period representative of the long-term runoff pattern, water years 1988–2013, were simulated

and provided to the trophic modeling team. 

Introduction

The Bureau of Reclamation (Reclamation) and the U.S. Geological Survey (USGS) are 

collaborating on a project in the Methow River Basin to merge a conceptual geomorphic-habitat model 

with a process-based trophic model (Bellmore and others, 2014) designed to aid in the understanding of 

how environmental variables and their relationship to one another influence fish production. The 

Methow River is one of several rivers selected to test these models at reach and watershed scales. The 

key hydrodynamic variables for the conceptual geomorphic-habitat model include discharge, changes in 

water-surface area, depths and velocities associated with discharge, wood and sediment accruals, bed 

slope, and bed scour. Although streamflow-gaging data are available at about a dozen locations in the 
2 

basin, daily discharge data are needed at many more stream locations in the basin. The USGS 

Washington Water Science Center previously developed a rainfall-runoff (watershed) model calibrated 

to observed runoff (Ely and Risley, 2001; Ely, 2003; Voss and Mastin, 2012); therefore, with some 

minor alterations to the model and the extension of the meteorological data input files through the end 

of water year 2013, a daily time series of runoff at many ungaged stream locations on the Methow River 

network could be simulated. 

Purpose and Scope

This report contains background information on the watershed model used to simulate runoff in 

the Methow River Basin and the results of those simulations. The previous model included input data 

from water years 1958 to 2001. The input data were updated through water year 2013 for this project. 

The original model included 48 stream locations where simulated data could be summarized and a daily 

time series of runoff could be generated. Thirteen new stream locations were added for this project at 

areas of interest to the team developing the conceptual geomorphic-habitat model and process-based

trophic model. All areas of interest were at locations representing small watersheds upstream of existing 

simulated stream locations. This report also contains summaries of mean monthly and mean annual 

simulated and observed data. Extensive calibration and parameter sensitivity analysis were done on the 

watershed model by Ely (2003), so no additional calibration of the model was performed as part of this 

project. 

Basin Description

The Methow River drains 1,820 mi2 in north-central Washington on the east side of the Cascade 

Mountains (fig. 1). The headwaters are along the crest of the Cascade Mountains at elevations as high as 

8,950 ft, and water generally flows in a southeasterly direction to the mouth at the confluence with the 

Columbia River near the town of Pateros (elevation 755 ft). Annual precipitation is greatest at the 

Cascade crest, with more than 70 in. that mostly is in the form of snow, and least near the Methow River 

mouth, with about 10 in. (climatological normal 1971–2000; Daly and others, 2002). 

Water availability in the Methow River Basin is vital for sustaining the local economy and the 

fragile ecosystem. Irrigation for agriculture accounts for 99 percent of the allocated water use as 

determined from water rights (Methow Basin Planning, 2005). In 2000, the basin contained 16,730 

acres of irrigated land, 77 percent of which were planted in alfalfa, and the remaining acreage primarily 

was orchards or pasture. Seepage from river channels, irrigated farmland, and unlined irrigation ditches 

recharges groundwater reservoirs (Konrad and others, 2003) that provide groundwater discharge 

necessary for maintaining wetlands, riparian habitat, and flows during the late summer and autumn. 

These summer and autumn flows are vital for supporting the Upper Columbia summer steelhead 

(Oncorhynchus mykiss) and spring Chinook (Oncorhynchus tshawytscha) salmon populations (which 

are both listed as endangered under the Endangered Species Act), as well as bull trout (Salvelinus 

confluentus) populations (listed as a threatened species). Water also is important for the growing 

tourism industry, which includes Nordic skiing, fishing, boating, and wildland recreation. 
3 

Figure 1. Map showing location of U.S. Geological Survey streamflow-gaging stations in the Methow River Basin, 

Washington. From Voss and Mastin (2012). 
4 

The climate varies from alpine conditions in the Methow River headwaters to semi-arid 

lowlands. The average annual precipitation for the basin is 31.9 in. (U.S. Geological Survey, 2011). 

Precipitation mostly is in the form of snow at higher elevations and mostly falls in the winter months.

This type of winter-snow precipitation climate results in a hydrology dominated by snowmelt runoff 

during the spring-early summer season. Two hydrographs are shown in figure 2— Andrews Creek, a 

small high-elevation watershed (streamflow gaging station is at an elevation of 4,300 ft) with a drainage 

area of 22.1 mi2; and Methow River near Pateros, a streamflow-gaging station near the mouth of the 

Methow River at an elevation of 900 ft with a drainage area of 1,772 mi2

. Andrews Creek has a mean

discharge of 32.6 ft3/s (water years 1969–2013) that is equivalent to an average runoff of 20.03 in. The 

Methow River near Pateros has a mean discharge (water years 1960–2013) of 1,558 ft3/s that is 

equivalent to an average runoff of 11.95 in.. Both streamflow hydrographs show a similar runoff pattern 

(fig. 2), with highest flows occurring in May and June in response to the snowmelt season. 

Figure 2. Graphs showing mean monthly discharge for water years 1988–2013 at two streamflow-gaging stations 

in the Methow River Basin, Washington. 
5 

Watershed Model

The watershed model used for this project is the Precipitation Runoff Modular System (PRMS; 

Leavesley and others, 1983). The model runs on a daily time step and requires daily precipitation and 

maximum and minimum daily air temperature as input to drive the model. PRMS is a physically based, 

distributed-parameter model that simulates runoff and snow accumulation and melt. The basin is 

partitioned into hydrologic response units (HRUs), which sometimes are referred to as model response 

units (MRUs) or units of land that have similar hydrologic responses to moisture and temperature 

inputs. A water budget is calculated for each HRU to estimate surface, subsurface, and groundwater 

outflow. Flow-routing segments (previously referred to as “nodes”) accumulate simulated runoff from 

the HRUs, route the flows to the next downstream segment, and provide daily simulated runoff to the 

user as output. 

Development of the Model for the Methow River Basin

The original PRMS watershed model was constructed for the Methow River Basin by Ely and 

Risley (2001) and was updated by Ely (2003). The updated Methow model included the simulation of 

diversions and applications of irrigation waters. The calibrated parameters and construction of this 

second version of the model is thoroughly explained by Ely (2003) and closely represents the model 

used for this project. The second version of the Methow model was developed on a UNIX® computer 

platform. Since that time, the PRMS model has been updated to run on a Microsoft Windows® operating 

system and code has been updated to accommodate GSFLOW, a coupled groundwater and surfacewater flow model that uses PRMS for the surface-water algorithms (Markstrom and others, 2008). 

GSFLOW has not been applied to the Methow River Basin. The PRMS updated model for Windows®

includes changes in several parameter names and a slight alteration of some of the algorithms. A third 

version of the Methow model was created using the Windows® version of PRMS by Voss and Mastin 

(2012). The parameters that were calibrated by Ely (2003) were used in this third version, but as a result 

of converting to the Windows® PRMS model, the simulations between the two versions of the model 

did not match exactly. A comparison of the simulated runoff was made by Voss and Mastin (2012) for 

the two versions of the model at 11 USGS streamflow-gaging stations in the Methow River Basin for 

water years 1960–2001. The simulated mean annual streamflow for the Windows® version of the 

Methow model was within 5 percent of the earlier simulations by Ely (2003) for all sites except for 

Beaver Creek (station 12449710), which was 8.8 percent different. This Windows® version of the 

Methow model (Voss and Mastin, 2012) is the same as the version used for this project, with the 

exception of some added stream segments as described in section, “Stream Segments.” The added 

stream segments do not affect the quantity of runoff simulated by the model. The added segments only 

provide additional locations where simulated runoff can be reported in the output file. 
6 

Construction of the PRMS Model for the Methow River Basin

The construction of the PRMS model for the Methow River Basin is thoroughly described by 

Ely and Riley (2001) and Ely (2003) and in less detail in this section of the report. The drainage network 

and HRUs were delineated with the geographic information system- (GIS-) based program called 

Weasel (Viger and others, 1998), with a digital elevation model (DEM) having regularly spaced 30-m 

cells as the primary input. The delineation of HRUs began with a two-flow-plane process that defined 

separate irregular polygons on each side of a stream reach. The HRUs were further divided by elevation 

zones at 1,000-ft intervals. The result was to define 620 HRUs for the entire basin, ranging in size from 

1.5 to 2.4 mi2

. 

Based on the map of HRUs, a topographic grid, a State Soil Geographic Database (STATSGO) 

GIS grid of generalized soil-survey data (U.S. Department of Agriculture, 1994), a GIS grid of forest 

density (Powel and others, 1998), and a GIS grid of land cover/land use (Loveland and others, 1991), 

the Weasel program computed most of the model parameters for the Methow model. Outside of the 

Weasel program parameters, such as the groundwater recession coefficients, monthly mean precipitation 

values for the HRUs and flow-routing parameters were computed or calibrated by comparing simulated 

and observed runoff.

Input Data File

The PRMS model is driven by input of daily minimum and maximum air temperature and daily 

precipitation from the input data file (table 1). The model uses an inverse-square distance weighting 

scheme to distribute the precipitation data from all precipitation inputs to estimate a daily precipitation 

total for each HRU. Daily minimum and maximum temperatures use a similar inverse-square distance 

interpolation scheme along with calculated lapse rates to distribute air temperature from all input sites to 

each of the HRUs (Mastin and Vaccaro, 2002). The input data file for the Methow model also contains 

daily discharge for 12 streamflow-gaging stations that are used for comparison with simulated discharge 

and that are not used in the simulations (table 1). After the initial header data, each row of data in the 

input data file corresponds to 1 day of data for the date provided in the second to fourth columns of data.

The data input file was extended from October 1, 2002 to September 30, 2013 for this project.

The locations of the sites represented in the data in the input data file are shown in figure 3. 
7 

Figure 3. Map showing data-collection network used for the watershed model for the Methow River Basin, 

Washington. From Ely (2003).
8 

Table 1. Streamflow-gaging and meteorological stations by agency collecting the data, period of record, and the 

position in the data input file, Methow River Basin, Washington. 

[Locations of stations are shown in figure 3. R, runoff; Precip., precipitation; Min., minimum; Max., maximum; Temp., temperature; --, not 

applicable] 

Station name 

(station No.) Period of record

Position in each row of data

in the input data file

R Precip. Min. Max.

U.S. Geological Survey streamflow-gaging stations

Lost River near Mazama (12447370) 2000–present 1 -- -- --

Early Winters Creek near Mazama (12447382) 2000–present 2 -- -- --

Methow River above Goat Creek near Mazama 

(12447383)

1991–present 3 -- -- --

Wolf Creek below Diversion near Winthrop 

(12447387)

2000–2003 4 -- -- --

Andrews Creek near Mazama (12447390) 1968 to present 5 -- -- --

Chewuch River below Boulder Creek near 

Winthrop (12447500)

No daily record 6 -- -- --

Chewuch River at Winthrop (12448000) 1992–present 7 -- -- --

Methow River at Winthrop (12448500) 1912 –present 8 -- -- --

Twisp R above Newby Creek near Twisp 

(12448990)

2000–2003 9 -- -- --

Twisp River near Twisp (12448998) 1976–present 10 -- -- --

Methow River near Twisp (12449500) 1919–present 11 -- -- --

Beaver Creek near Mouth near Twisp (12449710) 2000–2001 12 -- -- --

Methow River at Pateros (12449950) 1959–present 13 -- -- --

National Weather Service meteorological stations

Chelan 1890–present -- 14 32 49

Chief Joseph Dam 1949–present -- 15 33 50

Conconully 1948–present -- 16 34 51

Mazama 1950–present -- 17 35 52

Mazama 6 1948–1976 -- 18 -- --

Methow 2 1957–1970 -- 19 36 53

Methow 2S 1970–present -- 20 37 54

Omak 1931–1998 -- 21 38 55

Omak 4 1980 –1991 -- 22 39 56

Ross Dam 1960–present -- 23 40 57

Stehekin 4 NW 1931–present -- 24 41 58

Tonasket 4 NNE 1984–present -- 25 42 59

Winthrop 1 WSW 1931–present -- 26 43 60

Natural Resources Conservation Service meteorological stations

Harts Pass 1981–1982, 1983–present -- 27 44 61

Pope Ridge 1981–present -- 28 45 62

Rainy Pass 1981–present -- 29 46 63

Salmon Meadows 1981–1982,1983–present -- 30 47 64

Thunder Basin 1989–present -- 31 48 65
9 

Diversions and Applications

Streamflow in most of the lower basin is affected by withdrawals of surface water for irrigation. 

Water removed from the rivers either is applied to the fields for irrigation or seeps from canals where 

they are unlined, contributing to the recharge of the local aquifer. The recharge from seepage is 

simulated by providing a HRU number that directs the seepage from a specified diversion to the 

simulated groundwater reservoir for that HRU. 

Based on discharge measurements documented by Klohn Leonoff, Inc. (1990) and Konrad and 

others (2003), Ely (2003) estimated that 50 percent of the diverted water is lost from the canal by 

seepage. This value was used by the Methow model in the simulation of all diversions. Ely (2003) 

estimated that irrigation was applied at an average rate of 0.2 in/d from May 1 through October 7, 

totaling 32 in. of water for the 160-day period and approximating the annual water requirement for 

alfalfa. A time series of 0.2 in/d throughout the irrigation season, May 1–October 7, was developed as a 

separate data file for simulating irrigation for water years 1988–2013. Another separate data file 

contains a daily time series of diversions for 16 irrigation canals based on reported values or as 

determined by Ely (2003) from the change in streamflow at the diversion point (table 2). The Beaver 

diversion represents a summation of many small diversions in the Beaver Creek area. The data file of 

daily diversions uses the same values (table 2) for every year of simulation for water years 1988–2013, 

with the exception of water years 2000 and 2001 when Early Winters and Wolf Creek ditches were shut 

down early. 
10 

Table 2. Simulated irrigation diversions, Methow River Basin, Washington.).

[Data from Ely (2003; table 3). Data position in the diversion data file is shown in parentheses beneath the diversion name. 

Abbreviations: Sept., September; MVID, Methow Valley Irrigation District; TVPI, Twisp Valley Power and Irrigation]

Date

Daily diversion rate, in cubic feet per second

Barkley

(1)

Beaver

(16)

Chewuch

(2)

Early 

winters (3)

Eightmile

(4)

Foghorn

(5)

Foster

(6)

Fulton

(7)

May 1–15 12 12 25 14 5 15 5 15

May 16–31 12 12 30 14 5 15 5 15

June 1–15 12 17 30 14 5 15 5 15

June 16–30 12 17 35 14 5 15 5 15

July 1–15 12 17 35 14 7 18 5 18

July 16–31 18 12 30 14 7 18 5 18

August 1–15 18 12 25 14 7 13 5 20

August 16–30 15 12 25 14 7 13 5 20

Sept. 1–15 15 12 25 14 7 10 5 17

Sept. 16–30 9 12 20 14 7 10 5 17

October 1–7 4.5 0 10 7 3.5 5 2.5 8.5

Date

KummHolloway

(8)

McKinney 

Mountain

(9)

MVID

East 

(10)

MVID 

West

(11)

Rockview

(12)

Skyline

(13)

TVPI

(14)

Wolf 

Creek

(15)

May 1–15 4.5 5 39 24 9 20 10 8

May 16–31 4.5 5 39 24 9 20 12 8 

June 1–15 4.5 5 41 24 9 22 11 8

June 16–30 4.5 3 41 24 9 22 11 8 

July 1–15 4.5 3 42 26 10 17 11 8

July 16–31 4.5 3 42 26 10 17 11 8

August 1–15 4.5 3 37 26 10 20 10 8 

August 16–30 4.5 3 37 26 10 20 9 8

Sept. 1–15 4.5 3 39 25 9 15 7 8 

Sept. 16–30 4.5 3 39 25 9 15 7 8

October 1–7 2.3 1.5 19.5 10 4.5 7.5 2.5 4
11 

Stream Segments

Stream segments represent the stream reaches, although they can be conceptualized as a point on 

the stream network that accumulates runoff from an upstream segment and (or) an upstream HRU 

runoff. A simple algorithm routes water from one segment to the next downstream segment. Model 

parameters are used to direct runoff from the HRUs to user-specified segments, and the parameters also 

direct routed streamflows from the segment to the next downstream segment. The segments also allow 

the user to output daily runoff to an ASCII file for each specified segment. The model was set up with 

211 segments, but only 48 segments were active in the sense that they were receiving runoff from 

HRUs, and the other segments were inactive or were not receiving runoff from HRUs. The inactive 

segments are simply connected to other segments and they do not affect the simulations. The active 

segments generally were located at the mouth of major tributaries and at streamflow-gaging stations so 

that simulated and observed runoff could be compared during the original calibration process. The 

Reclamation-USGS team developing the trophic-geomorphic model for the Methow River Basin 

requested additional daily time series of simulated discharge to represent catchments upstream of the 

existing network of active segments. Thirteen additional segments were activated for this project. Some

of the HRUs that were upstream of the new segments and that originally were supplying runoff to an 

existing active segment now are supplying runoff to a newly activated segment. The runoff accumulated 

in the newly activated segment is routed downstream to the existing active segment. Thus, all runoff is 

conserved and tests showed that the resulting runoff hydrograph with the new activated segments is 

almost identical to the hydrographs simulated by the original model with slight differences (less than 1 

percent) owing to changes in travel time. The location and segment number for all segments receiving 

HRU runoff as point features are shown in figure 4. A total of 61 active segments are in the current 

watershed model, and a time series of simulated runoff at each of the segments was generated and 

provided to the Reclamation-USGS team.
12 

Figure 4. Map showing U.S. Geological Survey (USGS) streamflow-gaging stations, flow-routing segments, and 

hydrologic response units for the watershed model for the Methow River Basin, Washington. 
13 

Simulated Runoff at Stream Locations

The watershed model was run from water years 1986 to 2013. The first two water years were

used as a “warm-up” period for the model to allow the various simulated moisture storages and 

variables to approach a true, stable condition. The effective period of simulation was from the beginning 

of water year 1988 to the end of water year 2013. This 26-year period seems to be fairly representative 

of the long-term hydrology of the basin. The annual mean runoff for this period is 1,537 ft3/s, as

recorded at the USGS streamflow-gaging station, Methow River near Pateros, Washington (station No. 

12449950), which is similar to the long-term mean runoff of 1,558 ft3/s at the same streamflow-gaging 

station (water years 1960–2013, fig. 5).

In order to assess the accuracy of the watershed model in simulating the general hydrology of the 

basin, mean monthly simulated and observed runoff were compared at six selected streamflow-gaging 

stations with the longest record of runoff (fig. 6). Several of the comparisons of simulated and observed 

runoff show a tendency to over-simulate runoff for October and November and under-simulate runoff 

for May and June. The difference between simulated and observed annual runoff ranged from +15.4 to 

-9.6 percent (appendix A) for the same stations shown in figure 6. The simulated and observed mean 

monthly data indicated a larger range of percent difference (appendix A). Ely (2003, p. 33) showed that 

the watershed model simulations “were less accurate at capturing the magnitude and timing of shortterm (1- to 3-day) peak flows.” For this reason and the fact that the model is simulating mean daily 

flows rather than a shorter time step more suited to simulated instantaneous peak flows, the runoff 

simulated by the watershed model should not be used for peak-flow analysis.

The simulated runoff output from the watershed model is sent to ASCII files, with each row of 

data containing 1 day of output. The order of the listed variables (segment_cfs in this case) in the header 

part of the data-output file corresponds to the order of variable value in each row of data to the right of 

the date information. Following segment_cfs is the index number of the variable that relates the values 

to the specific location on the stream network (fig. 4), and the tosegment model variable is the segment 

downstream that receives the runoff from the indicated segment (table 3). The output file was copied to 

a spreadsheet and posted on the USGS Washington Water Science Center Methow Project Web site data 

page (http://wa.water.usgs.gov/projects/methow/data.htm).
14 

Figure 5. Graph showing annual mean runoff for Methow River near Pateros, Washington (USGS Station No.

12449950). 
15 

Figure 6. Graphs showing simulated and observed mean monthly runoff for indicated water years (WY) for six 

selected streamflow-gaging stations in the Methow River Basin, Washington. 
16 

Figure 6—Continued. 
17 

Table 3. Index value for the flow-routing variables segment_cfs and tosegment in the Methow watershed model 

and the associated streamflow-gaging station and period of record if co-located or the stream location.

[A tosegment index value of “0” indicates the final segment. Abbreviations: USGS, U.S. Geological Survey; POR, Period of record; 

Misc. Meas., Miscellaneous discharge measurements; NA, not applicable] 

segment_cfs

index 

number

tosegment

index 

number

USGS 

station

No. 

USGS- streamflow-gaging

station (in bold) or stream location

POR, observed 

record

water years

5 10 Lost River above Eurida Creek1 NA

10 11 12447370 Lost River near Mazama 2001–03

15 20 Early Winters Creek below Varden Creek1 NA

20 144 12447382 Early Winters Creek near Mazama 2001–03

30 149 Goat Creek NA

35 36 12447387 Wolf Creek below Diversion near Winthrop 2001–03

40 158 Wolf Creek NA

41 42 12447390 Andrews Creek near Mazama 1968–present

43 45 Lake Creek above Disaster Creek1 NA

44 64 Andrews Creek at mouth NA

45 65 Lake Creek at mouth NA

46 70 Twenty Mile Creek at mouth NA

47 75 Falls Creek at mouth NA

48 77 Eightmile Creek at mouth NA

49 80 Boulder Creek at mouth NA

62 64 Chewuch River below Meadow Creek1 NA

64 65 Chewuch River above Andrews Creek NA

65 66 Chewuch River above Lake Creek NA

70 71 Chewuch River below Twenty Mile Creek NA

75 76 Chewuch River below Falls Creek NA

77 78 Chewuch River below Eightmile Creek NA

80 81 12447500 Chewuch River Below Boulder Creek near 

Winthrop

Misc. Meas. 

only

88 161 12448000 Chewuch River at Winthrop 1992–present

90 92 Twisp River above South Creek1 NA

92 94 Twisp River above Reynolds Creek1 NA

94 100 Twisp River above War Creek1 NA

96 100 Buttermilk Creek below West Fork1 NA

98 100 Little Bridge Creek near mouth1 NA

100 101 12448990 Twisp River above Newby Creek near Twisp 2001–03

104 105 Twisp just below 12448990 NA

109 110 Twisp just above 12448998 NA

111 112 12448998 Twisp River near Twisp 1976–present

112 171 Twisp River at mouth NA

114 126 Libby Creek below Hornet Draw1 NA

116 117 Gold Creek below Foggy Dew Creek1 NA

117 127 Gold Creek below Middle Fork1 NA

118 127 South Fork below Rainy Creek1 NA
18 

segment_cfs

index 

number

tosegment

index 

number

USGS 

station

No. 

USGS- streamflow-gaging

station (in bold) or stream location

POR, observed 

record

water years

120 121 Beaver Creek below South Fork Beaver Creek NA

124 177 12449710 Beaver Creek near Mouth near Twisp 2001

125 180 Benson Creek at mouth NA

126 186 Libby Creek at mouth NA

127 191 Gold Creek at mouth NA

128 193 McFarland Creek at mouth NA

129 198 French Creek at mouth NA

130 201 Squaw Creek at mouth NA

131 203 Black Canyon Creek NA

139 140 Methow Headwaters NA

144 145 Methow River below confluence with Early 

Winters NA

148 149 12447383 Methow River above Goat Creek near Mazama 1991–present

158 159 Methow below confluence with Wolf Creek NA

162 163 12448500 Methow River at Winthrop 1912–present

165 166 Methow River below Bear Creek NA

167 168 Methow River. near Airport NA

172 173 12449500 Methow River near Twisp 1919–2013

177 178 Methow River below Beaver Creek NA

186 187 Methow River above Goat Creek near Mazama NA

191 192 Methow River below confluence with Gold Creek NA

193 194 Methow River above McFarland Creek NA

198 199 Methow River at confluence with French Creek NA

204 205 12449950 Methow River near Pateros 1959–present

211 0 Methow River at mouth NA

1

New sites added to the flow-routing network for this report.
19 

Summary 

A collaborative Bureau of Reclamation (Reclamation)-U.S. Geological Survey (USGS) effort to 

incorporate a conceptual geomorphic-habitat model with a process-based trophic model (for a better

understanding of the processes important to stream habitat for anadromous fish populations) will be 

tested in the Methow River Basin, and the effort requires runoff information at many stream locations in 

the basin. An existing watershed model was available to provide long-term simulated daily discharge 

data at many stream locations beyond what was available from the network of existing streamflowgaging stations. 

This report documents the changes that were made to the existing watershed model to 

accommodate the needs of the Reclamation-USGS effort to test the hybrid geomorphic-habitat/trophic 

model. It also provides some basic descriptions of the model (previous publications provide much more 

detail about the model). No changes were made to the parameter file of the watershed model that 

affected the simulation of runoff, except for the “activation” of some streamflow routing segments to 

augment the number of locations in the basin where runoff information could be simulated. Thirteen

new locations were added for a total of 61 sites in the basin where runoff was simulated. The input data 

file that drives the watershed model was updated to include maximum and minimum daily air 

temperature and daily precipitation through water year 2013. Time series of simulated daily runoff for 

each of the 61 sites were generated for the period beginning in water year 1988 through the end of water 

year 2013 and were provided to the entire modeling team.

Comparisons of the simulated and observed runoff at six selected long-term streamflow-gaging 

stations showed that the simulated annual runoff was within +15.4 to -9.6 percent of the annual 

observed runoff. The simulated runoff generally matched the seasonal flow patterns, with bias at some 

stations indicated by over-simulation of the October–November late autumn season and undersimulation of the snowmelt runoff months of May and June. 

References Cited

Bellmore, J.R., Femier, A.K., Mejia, Francine, and Newsom, Michael, 2014, The response of stream 

periphyton to Pacific salmon—Using a model to understand the role of environmental context: 

Freshwater Biology, v. 59, p. 1,437–1,451. 

Daly, C., Gibson, W.P., Taylor, G.H., Johnson, G.L., and Pasteris, P., 2002, A knowledge-based 

approach to the statistical mapping of climate: Climate Research, v. 22, p. 99–113. 

Ely, D.M., 2003, Precipitation-runoff simulations of current and natural streamflow conditions in the 

Methow River Basin, Washington: U.S. Geological Survey Water-Resources Investigations Report 

2003-4246, 35 p. [Also available at http://pubs.usgs.gov/wri/wri034246/.] 

Ely, D.M., and Risley, J.C., 2001, Use of a precipitation-runoff model to simulate natural streamflow 

conditions in the Methow River Basin, Washington: U.S. Geological Survey Water-Resources 

Investigations Report 2001-4198, 36 p. [Also available at http://pubs.usgs.gov/wri/wri014198/.] 

Klohn Leonoff, Inc., 1990, Water management plan for Methow Valley Irrigation District: Richmond, 

British Columbia, Klohn Leonoff, Inc., 74 p. 

Konrad, C.P., Drost, B.W, and Wagner, R.J., 2003, Hydrogeology of the unconsolidated sediments, 

water quality, and ground-water/surface-water exchanges in the Methow River Basin: U.S. Geological 

Survey Water-Resources Investigations Report 03-4244, 137 p. 
20 

Leavesley, G.H., Lichty, R.W., Troutman, B.M., and Saindon, L.G., 1983, Precipitation-runoff 

modeling system–User’s manual: U.S. Geological Survey Water-Resources Investigations Report 83-

4238, 207 p. [Also available at http://pubs.er.usgs.gov/publication/wri834238.] 

Loveland, T.R., Merchant, J.W., Ohlen, D.O., and Brown, J.F., 1991, Development of a land cover 

characteristics database for the conterminous U.S.: Photogrammetric Engineering and Remote 

Sensing, v. 57, no. 11, p. 1,453-1,463. 

Markstrom, S.L., Niswonger, R.G., Regan, R.S., Prudic, D.E., and Barlow, P.M., 2008, GSFLOW—

Coupled ground-water and surface-water flow model based on the integration of the Precipitationrunoff modeling system (PRMS) and the modular ground-water flow model (MODFLOW-2005): 

U.S. Geological Survey Techniques and Methods, book 6, chap. D1, 240 p. [Also available at 

http://pubs.usgs.gov/tm/tm6d1/.] 

Mastin, M.C., and Vaccaro, J.J., 2002, Documentation of precipitation-runoff modeling system modules 

for the Modular Modeling System modified for the Watershed and River Systems Management 

Program: U.S. Geological Survey Open-File Report 02-362, 5 p. 

Methow Basin Planning, 2005, Methow Basin (WRIA 48) Watershed Plan: Methow Basin Planning 

Unit, 50 p., accessed January 10, 2012, at 

http://okanogancounty.org/water/Documents%20on%20Site/Methow%20Basin%20plan%20text.pdf. 

Powell, D.S., Faulkner, J.L., Darr, D., Zhu, Z., and MacCleery, D.W., 1998, Forest resources of the 

United States, 1992: Fort Collins, Colorado: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Forest and Range Experiment Station, General Technical Report. 

U.S. Department of Agriculture, 1994, State Soil Geographic (STATSGO) database—Data use 

information: Fort Worth, Texas, Soils Conservation Service, National Cartography and GIS Center. 

U.S. Geological Survey, 2011, StreamStats: U.S. Geological Survey, accessed October 30, 2014, at 

http://water.usgs.gov/osw/streamstats/Washington.html. 

Viger, R.J., Markstrom, S.L., and Leavesley, G.H., 1998, The GIS Weasel—An interface for the 

treatment of spatial information used in watershed modeling and water resource management, in 

Proceedings of First Federal Interagency Hydrologic Modeling Conference, April 19–23, 1998, Las 

Vegas: Nevada, Interagency Advisory Committee on Water Data, v. 2, chap. 7, p. 73-80. 

Voss, F.D., and Mastin, M.C., 2012, Simulation of streamflows and basin-wide hydrologic variables 

over several climate-change scenarios, Methow River Basin, Washington: U.S. Geological Survey 

Scientific Investigations Report 2012-5031, 18 p. 
21 

Appendix A. Simulated and Observed Mean Monthly and Annual Runoff for Six 

Streamflow-Gaging Stations for the Period of Record that the Station Was Active 

During Water Years 1988–2013

Water years 1993–2013 Methow River above Goat Creek near Methow, station No. 12447383

OCT NOV DEC JAN FEB MAR APR

Observed runoff 54 129 66 41 30 96 571

Simulated runoff 299 385 157 147 119 153 446

Percent difference 454.4 198.6 137.6 258.9 296.7 59.3 -22.0

MAY JUNE JULY AUG SEPT ANNUAL

Observed runoff 2,050 2,200 847 167 47 516

Simulated runoff 1,539 2,129 1,099 429 235 596

Percent difference -24.9 -3.2 29.8 157.0 399.4 15.4

Water years 1988–2013 Andrews Creek near Mazama, station No. 12447390

OCT NOV DEC JAN FEB MAR APR

Observed runoff 7.9 8.4 6.2 5.2 4.8 5.9 30.0

Simulated runoff 7.4 7.8 5 5.1 5.1 5.2 18

Percent difference -6.3 -7.1 -19.4 -1.9 6.3 -11.9 -40.0

MAY JUNE JULY AUG SEPT ANNUAL

Observed runoff 130.0 135.0 44.0 14.0 8.2 33.4

Simulated runoff 124.5 137 45.7 13.7 7.6 31.9

Percent difference -4.2 1.5 3.9 -2.1 -7.3 -4.4

Water years 1992–2013 Chewuch River at Winthrop, station No. 12448000

OCT NOV DEC JAN FEB MAR APR

Observed runoff 106 112 89 78 78 117 476

Simulated runoff 132 173 118 124 137 183 445

Percent difference 24.1 54.5 32.1 59.0 76.2 56.7 -6.4

MAY JUNE JULY AUG SEPT ANNUAL

Observed runoff 1,690 1560 484 150 85 420

Simulated runoff 1,297 1345 385 133 76 379

Percent difference -23.2 -13.8 -20.4 -11.1 -10.0 -9.6
22 

Water years 1991–2013 Methow River at Winthrop, station No. 12448500

OCT NOV DEC JAN FEB MAR APR

Observed runoff 308 424 329 282 275 435 1,420

Simulated runoff 472 727 339 340 354 472 1,102

Percent difference 53.3 71.6 2.9 20.5 28.6 8.5 -22.4

MAY JUNE JULY AUG SEPT ANNUAL

Observed runoff 4,440 4,310 1,630 500 280 1,202

Simulated runoff 3,250 3,750 1,540 581 311 1,105

Percent difference -26.8 -13.0 -5.5 16.3 11.2 -8.1

Water years 1988–2013 Twisp River near Twisp, station No. 12448998

OCT NOV DEC JAN FEB MAR APR

Observed runoff 63 111 81 72 74 120 341

Simulated runoff 97 174 71 77 78 119 353

Percent difference 54.0 57.0 -12.3 7.2 5.3 -0.8 3.4

MAY JUNE JULY AUG SEPT ANNUAL

Observed runoff 885 941 380 92 43 267

Simulated runoff 734 817 359 108 47 253

Percent difference -17.0 -13.1 -5.5 17.5 8.1 -5.3

Water years 1988–2013 Methow River at Pateros, station No. 12449950

OCT NOV DEC JAN FEB MAR APR

Observed runoff 437 583 478 415 407 598 1,840

Simulated runoff 597 1,025 563 605 666 922 1,934

Percent difference 36.7 75.8 17.7 45.7 63.6 54.1 5.1

MAY JUNE JULY AUG SEPT ANNUAL

Observed runoff 5,190 5,320 2,090 665 397 1,515

Simulated runoff 4,180 4,738 1,948 700 348 1,520

Percent difference -19.5 -10.9 -6.8 5.3 -12.3 0.3
Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

 Director, Washington Water Science Center

U.S. Geological Survey

934 Broadway, Suite 300

Tacoma, Washington 98402 

http://wa.water.usgs.gov
Mastin—Simulated Runoff at Many Locations in the Methow River Basin, Washington

—Open-File Report 2015-1011

ISSN 2331-1258 (online)

http://dx.doi.org/10.3133/ofr20151011